3. Lac i is translated into the repressor protein, which is inhibited by allolactose and so does not bind to the operator. cAMP is not abundant, so not CAP-cAMP complex binds the CAP site. Weak transcription results.

What is the entropic effect?

The energetically favourable clustering of hydrophobic amino acid residues into the center of the protein so as to prevent water caging which defies entropy.

The G-coupled protein receptor. Consists of 7-transmembrane subunits. When a receptor is activated, it induces conformational change in the Gα subunit, which dissociates GDP and binds GTP, becoming active. Gα dissociates from other subunits and activates effector molecule. GTP is hydrolysed to GDP, Gα reassociates with subunits.

Give the two adrenaline receptors.

α-adrenogenic and β-adrenogenic receptors.

What are the regulatory points in Krebs cycle?

Steps 1, 3 and 4. Step 3 is a critical step.

Outline the progression of chemicals in Krebs cycle.

1. Citrate.

2. Isocitrate.

3. α-ketoguterate.

4. Succinyl Co-A

5. Succinate

6. Fumarate

7. Malate

8. Oxaloacetate.

Give the enzymes in Krebs cycle and the processes they catalyse, in order.